Sealed pressure containers such as approved by the U.S. Department of Transportation (DOT) are gaining popularity as vessels for storing and delivering fluids. Some of the advantages gained by using pressure containers include enhanced health and safety since DOT pressure containers resist slitting and leakage, decreased environmental impact due to a lower probability of fluid being inadvertently released from sealed pressure container, more efficient fluid transfer capabilities between the container and the destination of the fluid (e.g. an automobile or other machine), and lower costs due to reusability of the pressure containers.
It is possible to place a charge of a gas, such as nitrogen or carbon dioxide, in a pressure container as a propellant, and use the propellant gas to dispense the fluid without pumps. Using a propellant gas has advantages because, particularly in the case where the propellant is an inert gases, the propellant provides an extra degree of fire safety, and largely eliminates the need for pumps and electronics.
In the case of pressure containers with inert gas propellant, it is desirable that during filling of the container with fluid, propellant gas is not allowed escape, otherwise the container will have an insufficient charge of propellant gas to delivery the fluid and will need to be recharged In this respect, filling pressure containers with fluid without the propellant gas escaping, can be a time-consuming and labor-intensive task. Generally, fluids are delivered from a larger container under high-pressure to a smaller pressure container under lower pressure. The transfer of fluid is typically accomplished utilizing pumps or other means. Often, the pumps that are used to transfer the fluid do so in pulsating, high-pressure spurts. Various means can be employed to ensure that the correct volume of fluid is delivered, and to prevent over or under filling of the pressure container with fluid. For example, systems that deliver a predetermined volume of fluid, such as by using fluid meters, are appropriate where the pressure container is known to be empty. Other systems utilize weighing systems that control a fluid valve to automatically shut off fluid flow when the container reaches a certain desired weight. These systems are not ideal because they require costly and sensitive meters, pumps, and electronics, and have reliability problems.
Therefore, there remains a need for an improved automatic pressure container filling valve/system which can be used to automatically and reliably control the flow of fluids from any fluid source, even under high and pulsating irregular pressure, to a pressure container under a gas blanket, to thereby fill the pressure container with the fluid until the propellant gas in the pressure container reaches a predetermined pressure.